There's been a lot of talk this month about what theatre can do. Some people want it to be like Batman, responding to crises almost before they've happened. Others believe that while theatre has a right to offend, apparently those offended by it shouldn't necessarily have a right to reply. Amid all this debate, it may have gone unnoticed that there has been an equally important exploration taking place – not about what theatre can do, but about how it does what it does.

Each night was a fascinating journey through the way we view art; the visual signs, the descriptions, the resonance of familiar images and statements. In their own diverse ways, all the productions played with the boundary between showing and telling. It's no surprise that these artists have been seen in major theatres across Europe and beyond, yet what is fascinating is that here, in London, they find themselves in an explicitly dance-focused venue – Sadler's Wells. Why is this? Why is it that artists as brilliantly diverse as Ivana Müller, Jérôme Bel, Ballets C de la B and, in March, Robert Lepage all find a home on Rosebery Avenue rather than the South Bank or the West End?

In part, it is down to the daring and ambitious programming of artistic director Alistair Spalding. Seasons such as the Jérôme Bel retrospective or Sadler's Wells' collaboration with the Gate Theatre demonstrate a willingness to test the limits of what might be considered dance, to forge new links with other mediums. Later this year, opera houses, art galleries and abandoned warehouses will become the site of this continued process of exploration. Of all of the city's premier-league venues, it's now the Sadler's Wells programme I look forward to reading about with the most anticipation.

But is there more to it than courageous programming? Is there something about Sadler's Wells' status as a major dance venue that lends itself more comfortably to engagement with these convention-defying pieces than say, the National or the Royal Court? Over hundreds of years, we've developed a series of performance mediums that have calcified their differences from each other, slowly building their own vocabularies and histories. In this country we have developed a brilliant tradition of text-based, narrative-driven theatre – one that should be cherished. Yet, in mainstream British theatre, this often means that the importance of how something is done, the politics and meaning conveyed through form and process, is overlooked. And so the formal experimentation in even a relatively traditional, text-based work – such as Katie Mitchell's version of Martin Crimp's Attempts on Her Life – is readily dismissed by many as distracting and unhelpful.

So is the vocabulary of mainstream contemporary dance, with its looser narrative conventions and its formal playfulness, better equipped to read the work of, say, a Jérôme Bel? Is it more open to blurring the lines between the conventions of dance and theatre? I'd like to hope so, but perhaps those with more experience of dance disagree. After all, despite the crammed houses, I was told by a Sadler's Wells staff member after one show that there was at least one person demanding their money back because, in their words, "it wasn't dance".

He was an 18th-century spy who loved to cross-dress and swordfight. Who better to stage his life than Sylvie Guillem, Alexander McQueen, Russell Maliphant and Robert Lepage? They tell Judith Mackrell how they pulled it off